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UTE S 'AATENT FFI@ *4" STEPHEN H. HEAD, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO HIMSELF AND' fh/l. P. PARROTT, OF SAME PLACE.

STEAltI-BOILER.

Specification of Letters Patent No. 26,002, dated `November 1, 1859'.

To all whom 'it may concern:

Be it known that I, STEPHEN H. HEAD, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Steam-Boilers, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which- Figure l is a perspective view of a boiler; Fig. 2 a longitudinal vertical section of the same; Fig. 3 a transverse vertical section through the middle of the furnace.

Boilers have been constructed with double furnaces where the combustion chamber was placed above the furnaces, the bottom of the chamber being formed of a horizontal water partition through openings in which the products of combustion passed from one or other of the furnaces, but the position of this chamber was detrimental to the rapid generation of steam in that part of the boiler immediately over the furnaces, on account of the horizontal water partition being interposed between the body of the fire in the furnaces and the crown sheet, while the steam formed in this water partition was compelled to traverse a considerable space horizontally before it could mingle with that in the body of the boiler. These difficulties have been overcome by my improved arrangement of placing the combustion cha-mber immediately in front of the furnaces, which allowed the fire in the furnaces to rise directly against the crown sheet; and allows the steam generated in the partition D to rise freely and vertically into the boiler. This arrangement of the combustion chamber also enables me to place the flue which connected the two furnaces, at the back o'f the furnaces so that the flame from one furnace as it passes to the other will impinge directly on the rear plate of the fire box which is generally the coolest and most diflicult to heat. Boilers have also been constructed with two furnaces having a lateral passage to connect one furnace with the other, and the application of dampers to compel the smoke to pass from one furnace over the incandescent fuel of the other, and thus promote combustion of the volatile gases. But this arrangement could not be applied advantageously to tubular boilers, because when one of the furnaces was shut off, all the products of combustion must pass through one half of the flues the other half being closed by the closed damper, and consequently would be inapplicable to locomotive boilers. By my arrangement of a chamber in front of the two furnaces, which is common to both the furnaces in whatever position the damper may be the products of combustion though coming from. one furnace only, passes through all the tubes or flues alike, because the dampers only change the line of draft through the furnaces, but do not prevent the products of combustion from taking` the entire series of flues or tubes, after they have passed through the furnace. Besides this chamber in front of thefurnaces, serves as a space through which a single damper that may shut off either furnace, or leave both open, can freely swing; and is moreover a combustioni chamber. This chamber at the front of the furnaces, and its objects and purposes in connection with the two furnaces and the lateral passage between them, is what constitutes the novel and useful feature of my invention.

To enable others skilled in the art to understand and use my invention I will proceed to describe the manner in which I have carried it out.

In the said drawings A is the boiler, B and C fire spaces or furnaces which are separated by the water space or partition D, and

arefed alternately by fuel introduced through the doors b, c. This partition D does not extend to the back of the furnace or that part in which the doors b, c, are placed but leaves a space or flue E of the whole height of the furnaces, the water in this partition is in communication with that in the boiler, thogh the upper part of the partition which is open, and also with that in the water space Z at the front of the furnaces.

A chamber F extends from the front of the two furnaces B and C and is in communication with them both, the passage from either furnace being commanded by a valve or damper f, which is pivoted on a rod e immediately in front of the partition D, (for the convenience of turning this rod it may extend up through the top of the boiler in a tube g, as shown in Figs. 2 and 3.) The front of the chamber F forms the flue or tube plate in which the boiler flues or tubes are inserted. The products of combustion coming from either one of the furnaces, enters the chamber F, and what 1s not consumed there by ignition, as well as the heat and flame, is free to take the entire series of 4 flues which connect with said chamber-and thus this system of furnaces may be made available for locomotive boilers, and with great advantage.

The following will be the operation of my improved arrangement of furnaces: Vhen it becomes necessary to replenish one of the furnaces with fuel (for example furnace C) the damper f is turned so as to shut off the communication between this furnace and the chamber F; the course of the smoke and gases from this fire will then be toward the back of the furnace as indicated by the arrow Fig. 2, through the fiue E, and over the fire in the furnace B, traversing the entire length of this furnace and being there consumed or nearly all consumed before they reach the chamber F. lVhen the other furnace is to be fed, the damper is turned to the other side, and the -current is reversed, or sent over the lire in the furnace C. Then both lires are in full operation and consequently not vgiving olf much smoke, the

damper f may be set in a straight line behind the partition D by which it will be in a measure protected from the full power of the flame.

The chamber F, besides giving space for 30 turning the damper f, also serves as a combustion chamber where the gases from the )fires which have not been previously con sumed are here mingled and burned before entering the ues or tubes and the heat is 35 

